Invariably, the resulting contours demonstrate a higher intelligibility close to the speech loudspeaker and a lower intelligibility close to the noise loudspeaker.
A gradual degradation of speech intelligibility is observed over the area between the two sources.
A marked deviation from this trend has been observed when there are non-native speakers of English present in the room.
Professor Campbell indicates that he has observed holes in the intelligibility map in the locations where non-native speakers were seated.
In one particular map, an oblong “hole” corresponds to the seat locations of three Asian students who speak English as a second language. The intelligibility scores of those seated behind the Asian students actually rose as the distance from the source increased.
The professor also notes that he observed a similar depression when three Argentinean students were seated together. Yet he’s quick to point out that these students are fluent English speakers, “in the sense that rapid colloquial two-way conversation was easy for them,” he explained.
Indeed more research is required before absolute conclusions can be drawn, but the repeated incidence of poor intelligibility scores particularly when viewed in comparison with the scores of native speakers of English is intriguing.
Professor Campbell intends to continue this research while introducing an additional twist. He feels that there is strong evidence supporting the notion that this language dependent intelligibility phenomenon is exacerbated through the introduction of panic.
This added stress seems to generate an environment in which the ability to focus on what is being said is significantly compromised. This inability to focus also seems to have greater impact upon non-native speakers who require this concentration for absolute comprehension. While this area is currently extremely developmental, the impact – if true – would be tremendous, particularly in emergency situations.
The Cause of Language Dependence
Due to the infancy of this exploration, hard evidence is tough to come by, and further research is required. But perhaps it is helpful to investigate why this phenomenon might exist and then arrive at a logical explanation for its cause.
The root of the problem lies in the phoneme – essentially, the smallest unit of speech. Phoneme are distinct sounds that are formed through the various combinations of letters employed in the written word.
“The phonemes of a language operate in an analogous way [to letters] and in fact alphabetic writing is derived originally from the phonemic system…”(From the book “Homo Loquens”, by Dennis Fry, page 12)
While there are only 26 letters in the English alphabet, there are over 40 phonemes, 20 of which are derived from the five vowels utilized in English word construction. This essentially proves that the uses of vowel sounds in English word enunciation are quite diverse.
“Languages differ from each other in their phoneme systems, just as they differ in grammar and vocabulary…. What the phoneme system does is to dictate for any language what particular sounds must be recognized as distinct from each other and what sound differences should be disregarded.” (“Homo Loquens”, page 15)
The phoneme differences between languages result in situations where distinct phonemes in the one language are interpreted as being the same by foreigners who are unused to the diverse pronunciations of a given lettering. This situation arises between any two languages.